This invention relates to improved apparatus for manipulating from a remote location a shroud tube that encloses the molten stream flowing from a bottom pour teeming vessel to a receiver, such as a tundish. More particularly, the invention involves a manipulator of simple, light-weight construction that can be operated by a single workman from a remote location for connecting the inlet end of a shroud tube to the discharge nozzle from a teeming vessel. The apparatus is also for imparting the compound movements necessary to extend the discharge end of the shroud tube through the limited access opening of a tundish cover.
It is desirable when pouring molten metal of certain compositions, such as aluminum-killed steels, to prevent contact of the metal with ambient air in order to protect against reoxidation of the metal. Receivers for such metals are, accordingly, usually provided with a closure cover containing an access opening of limited dimensions and shroud tubes are commonly provided to enclose the molten stream from the teeming vessel to the receiver.
Shroud tubes for such service are formed of refractory material that is subject to erosion and wear, and therefore the tubes must be periodically replaced, oftentimes, before the teeming vessel has been emptied. In such instances, it had been the practice to terminate the pour whereupon one or more workmen would manually remove the spent tube and install a new one, a practice that is both arduous and hazardous.
In U.S. Pat. No. 4,131,220, granted Dec. 26, 1978 to Bode et al and assigned to the assignee herein, there is shown and described a manipulator for shroud tubes that enables the replacement of spent pour tubes from a remote location. While such apparatus is effective for the purpose intended, it is unduly bulky in size and of complicated design. This apparatus, moreover, incorporates numerous hydraulic operators that not only add to the capital cost of the apparatus but also require ancillary sources of hydraulic power that increase the cost of operation.
It is to the improvement of such apparatus, therefore, that the present invention is directed.